2/3

4

\(\dfrac{13}{15}-\dfrac{1}{5}=\dfrac{13}{15}=\dfrac{3}{15}=\dfrac{10}{15}=\dfrac{2}{3}\)

\(\dfrac{7}{8}\times\dfrac{2}{7}=\dfrac{14}{56}=\dfrac{1}{4}\)

\(\frac{7}{15}+\frac{2}{10}=\frac{14}{30}+\frac{6}{30}=\frac{20}{30}=\frac{2}{3}\)

\(\frac{8}{3}+\frac{4}{3}=\frac{12}{3}=\frac{4}{1}=4\)

a, \(\frac{7}{15}+\frac{2}{10}=\frac{2}{3}\)

b,\(\frac{8}{3}+\frac{4}{3}=4\)

\(\frac{7}{15}\)\(+\frac{2}{10}\)\(=\frac{2}{3}\)

\(\frac{8}{3}\)\(+\frac{4}{3}\)\(=4\)

8/9 : 10/6 : 12/25 : 14/18 = 10/7

10/7 nha

= \(\frac{10}{7}\)nha bạn

kết bạn nha 

5/12 + 3/9 + 4/36 = 31/36

\(\frac{5}{12}+\frac{3}{9}+\frac{4}{36}\)

=\(\frac{15}{36}+\frac{12}{36}+\frac{4}{36}\)

= \(\frac{15+12+4}{36}\)

= \(\frac{31}{36.}\)

31/36

\(\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\)

\(=\frac{1\times2\times3}{2\times3\times4}\)

\(=\frac{1}{4}\)

1/2 x 2/3 x 3/4 = 1/3 x 3/4 = 1/4

hok tốt

1/2 . 2/3 . 3/4

= 1/3 . 3/4

= 1/4

\(\dfrac{3}{7}:x=\dfrac{5}{7}\)

      \(x=\dfrac{3}{7}:\dfrac{5}{7}\)

     \(x=\dfrac{3}{7}\times\dfrac{7}{5}\)

     \(x=\dfrac{21}{35}\) 

     \(x=\dfrac{3}{5}\)

\(\dfrac{3}{7}:x=\dfrac{5}{7}\\ x=\dfrac{3}{7}:\dfrac{5}{7}\\ x=\dfrac{3}{5}\)

Vậy `x=3/5`

`@An`

8 : 16/23 = 8 × 23 : 16

= 23/2

92/3